Originally Posted by
Retro Grouch
I agree that's not much to go on. Just for fun, grab the top of your rear tire and try to wiggle it from side-to-side. If it moves, you've got loose hub bearings and that needs to be fixed pronto.
I checked this and it's definitely not an issue (thank goodness)
I'll take a closer look at the chainstay when it gets lighter out...